This invention relates to a method of producing a semiconductor device, such as a JFET, that is freely suspended upon a flexible microcircuit, and more particularly, to a means of joining the flexible microcircuit to the semiconductor with electrical connection therebetween.
In the past, various means have been used for attaching conductors to semiconductor devices, including the use of gold ball bonding machines that are specifically manufactured for providing wiring to semiconductors. In the typical use of a ball bonding machine a gold capillary wire is positioned over the conductive layer on the semiconductor device by means of a built-in microscope. A gold ball is formed on the free end of the capillary wire and the capillary wire is thus positioned to touch the desired conductive area of the semiconductor device. A combination of heat and ultrasonic energy is applied by the gold ball bonding machine to heat the gold capillary wire and thereby attach the gold ball to the conductive surface of the semiconductor device. The gold ball bonding machine is then moved to a second location normally on a gold plated can to which the semiconductor device is affixed and the capillary gold wire is played out through a needle to move to the second location where the machine again positions that wire to a desired location on the gold can and a wedge bond is formed, again by the application of heat and ultrasonic energy. Upon removing the machine from the wedge bond, the capillary gold wire normally breaks off from stresses encountered in forming the wedge bond, thereby leaving only a gold connection wire acting as a conductor between the semiconductor device and its mounting can.
In following the procedure of conventional gold ball bondinq machines, therefore, two connections are normally made with the gold capillary wire. The first is a gold ball bond that is applied to one of the conductive surfaces of the semiconductor device and the second is a wedge bond on the supporting can, the gold capillary wire joins the two bonds and provides an electrical connection between the supporting can and the extremely tiny microscopic conductive portions of the semiconductor device.